Where mechanical machining is performed by a drilling machine, boring lathe or grinding machine, the vibration of the rotary tool presents a serious problem. One of the causes of teh problem is considered to be the forced vibration due to the rotary tool being or becoming unbalanced.
As one example of a conventional rotary tool, there is a tool holder (a) shown in FIG. 5, which is provided with a clamp section (b) for an automatic tool exchanger. The tool holder has at one end thereof a tapered shank (c) and a tool mounting section (d) at the other end thereof, with the clamp section (b) being provided with an engaging groove cominginto engagement with the main spindle of a machine tool.
Where the too holder (a) is used with a highspeed rotary too, it is subjected to a balancing test using a balancing machine. The angle of the tool holder and the weight thereof corresponding to that angle are indicated by the blaancing machine. When teh weight of the tool holder is large, the excess portion of the holder is removed by cutting, thereby correcting the unbalanced condition of the holder.
However, the above-mentioned unbalancing correcting method requires skill and a considerable amount of time. In order to obtain a high degree of accuracy of balancing, it is extremely cumbersome, which results in lowering the working efficiency to a considerable degree.
The present device has been made in view of the above-described situation. Accordingly, an object of the present device is to provide a rotary tool which is capable of being balanced easily, accurately and efficiently.